A salicide barrier layer (SAB) is used to protect a surface of a silicon wafer, and under its protection, the silicon wafer does not form an undesired metal salicide with other metals such as Ti and Co.
In most processes, an oxide layer is generally used as a salicide barrier layer. In a manufacturing process, an oxide layer (hereinafter referred to as a “salicide barrier oxide layer”) used as a salicide barrier layer needs to be etched to form a patterned salicide barrier oxide layer. In this way, no metal salicide is formed on the surface of the silicon wafer below the patterned salicide barrier oxide layer after etching is performed, but a metal salicide will be formed on the surface of the silicon wafer where the salicide barrier oxide layer has been removed.
At first, salicide barrier oxide layers are generally etched by using a simple dry etching process. However, such a method is usually suitable for etching a salicide barrier oxide layer having only a thickness approximately equal to or greater than 1500 Å.
With the development of the processes, the following solution has been developed: a salicide barrier oxide layer is first partially etched by dry etching and the salicide barrier oxide layer is subsequently etched by wet etching. However, due to isotropy in a wet etching process, an arc-shaped topography structure is finally formed. The topography is disadvantageous for deposition of subsequent conductive substances, and a defect such as a void is easily formed, causing an electrical leakage or a breakdown to easily occur in a finally formed device structure, and affecting performance of the device.